Curnoe D
Sterkfontein Research Unit, School of Anatomical Sciences, Medical School, University of the Witwatersrand, 7 Parktown Road, Parktown 2193, Johannesburg, South Africa.
Homo. 2003;53(3):225-34. doi: 10.1078/0018-442x-00048.
Cladistic analysis is a popular method for reconstructing evolutionary relationships on the human lineage. However, it has limitations and hidden assumptions that are often not considered by palaeoanthropologists. Some researchers who are opposed to its use regard cladistics as the preferred method for taxonomic "splitters" and claim it has lead to a revitalisation of typology. Typology remains a part of human evolutionary studies, regardless of the acceptance or use of cladistics. The assumption/preference for "splitting" over "lumping" in cladistics (alpha) taxonomy and the general failure to evaluate (post-hoc) such taxonomies have served to reinforce this assertion. Researchers have also adopted a number of practices that are logically untenable or introduce considerable error. The evolutionary trend of human encephalisation, apparently isometric with body size, and concurrent reduction in the gut and masticatory apparatus, suggests continuous cladistic characters are biased by problems of body size. The method suffers a logical weakness, or circularity, leading to bias when characters with multiple states are used. Coding of such characters can only be done using prior criteria, and this is usually done using an existing phylogenetic scheme. Another problem with coding character states is the handling of variation within species. While this form of variation is usually ignored by palaeoanthropologists, when characters are recognised as varying, their treatment as a separate state adds considerable error to cladograms. The genetic proximity of humans, chimpanzees and gorillas has important implications for cladistic analyses. It is argued that chimpanzees and gorillas should be treated as ingroup taxa and an alternative outgroup such as orangutans should be used, or an (hypothetical) ancestral body plan developed. Making chimpanzees and gorillas ingroup taxa would considerably enhance the biological utility of anthropological cladograms. All published human cladograms fail to meet standard quality criteria indicating that none of them may be considered reliable. The continuing uncertainty over the number and composition of fossil human species is the largest single source of error for cladistics and human phylogenetic reconstruction.
支序分析是重建人类谱系进化关系的一种常用方法。然而，它存在一些局限性和隐藏假设，古人类学家往往并未加以考虑。一些反对使用该方法的研究人员认为，支序分析是分类学“细分者”的首选方法，并声称它导致了类型学的复兴。无论支序分析是否被接受或使用，类型学仍然是人类进化研究的一部分。支序分类学（α分类学）中“细分”而非“归并”的假设/偏好，以及普遍未能对这类分类法进行（事后）评估，都强化了这一观点。研究人员还采用了一些在逻辑上站不住脚或会引入重大误差的做法。人类脑容量增大的进化趋势，显然与身体大小呈等比关系，同时肠道和咀嚼器官缩小，这表明连续的支序特征受到身体大小问题的影响而产生偏差。该方法存在逻辑缺陷或循环性，在使用具有多种状态的特征时会导致偏差。此类特征的编码只能使用先前的标准来完成，而这通常是根据现有的系统发育方案进行的。编码特征状态的另一个问题是物种内变异的处理。虽然古人类学家通常会忽略这种变异形式，但当特征被认为存在变异时，将其作为一个单独的状态来处理会给支序图增加相当大的误差。人类、黑猩猩和大猩猩在基因上的相近性对支序分析具有重要意义。有人认为，应将黑猩猩和大猩猩视为内群分类单元，并使用诸如猩猩等替代外群，或者制定一个（假设的）祖先身体结构。将黑猩猩和大猩猩作为内群分类单元会大大提高人类学支序图的生物学实用性。所有已发表的人类支序图均未达到标准质量标准，这表明它们都不可被视为可靠的。化石人类物种数量和组成的持续不确定性是支序分析和人类系统发育重建最大的单一误差来源。
